Spectacle lens for a display device that can be fitted on the head of a user and generates an image, and display device with such a spectacle lens

ABSTRACT

A spectacle lens for a display device that can be fitted on the head of a user and generate an image guides light bundles of pixels of the generated image, which are coupled into the spectacle lens via the coupling-in section of the spectacle lens, in the spectacle lens by reflections on the rear side and a reflecting surface lying opposite this to the coupling-out section and coupling them out of the spectacle lens via the coupling-out section. A splitter layer reflects a portion of light bundles reflected by the rear side towards the rear side and transmits a portion, wherein after reflection on the rear side the reflected portion strikes the splitter layer again and there, once again, is partially reflected towards the rear side and partially transmitted. The transmitted portions strike the facets are coupled out of the spectacle lens through the splitter layer and the rear side.

PRIORITY

This application is a continuation of U.S. patent application Ser. No.15/024,854, which has a 371(c) date of Mar. 25, 2016, which was a U.S.National Phase application of PCT Application No. PCT/EP2014/070554,filed Sep. 25, 2014, which claims the benefit of German PatentApplication No. 102013219623.7 filed on Sep. 27, 2013, all of which arehereby incorporated herein by reference in their entirety.

FIELD

The present invention relates to a spectacle lens for a display devicethat can be fitted on the head of a user and generates an image, and adisplay device with such a spectacle lens.

BACKGROUND

Spectacle lenses often comprise, seen in top view onto the spectaclelens, a coupling-in section in an edge area of the spectacle lens and acoupling-out section in a central area of the spectacle lens, whereinlight bundles of pixels of the generated image, which are coupled intothe spectacle lens via the coupling-in section of the spectacle lens,are guided in the spectacle lens to the coupling-out section and coupledout of the spectacle lens via the coupling-out section in order toprovide a virtual image. In practice, it has been shown that it isdifficult on the one hand to form the spectacle lens as thin as possibleand on the other hand to provide as large as possible an exit pupil forthe coupled-out light beams. As a rule, therefore, so-called pupilexpanders are formed in the coupling-out section in order to realize thedesired expansion of the exit pupil. These are often formed asdiffractive pupil expanders which on the one hand display a strongdependency on wavelength and on the other hand are difficult to realize.

SUMMARY

An object of the invention is to provide a spectacle lens with which thedifficulties named above can be overcome as completely as possible.

The disclosure includes a spectacle lens for a display device that canbe fitted on the head of a user and generates an image, wherein thespectacle lens comprises a spectacle lens body comprising a front sideand a rear side, wherein the front side and/or the rear side is/arecurved and the spectacle lens body comprises a first and a secondpartial body, the mutually facing boundary surfaces of which areconnected to each other, and, seen in top view onto the spectacle lens,a coupling-in section in an edge area of the spectacle lens and areflective coupling-out section, which comprises reflective facets, in acentral area of the spectacle lens, as well as a splitter layer arrangedbetween the two boundary surfaces in the area of the coupling-outsection, wherein the spectacle lens is suitable for guiding lightbundles of pixels of the generated image, which are coupled into thespectacle lens via the coupling-in section of the spectacle lens, in thespectacle lens by reflections on the rear side and a reflecting surfacelying opposite this to the coupling-out section and coupling them out ofthe spectacle lens via the coupling-out section, wherein the splitterlayer in each case reflects a portion of light bundles reflected by therear side towards the rear side and transmits a portion, wherein afterreflection on the rear side the reflected portion strikes the splitterlayer again and there, once again, is partially reflected towards therear side and partially transmitted, wherein the transmitted portionsstrike the facets, which bring about a reflection in the direction ofthe rear side such that a coupling-out takes place through the splitterlayer and the rear side.

The desired widening of the pupil can be achieved easily with thisspectacle lens because it is ensured by means of the splitter layer thatthe light bundles (or the respectively transmitted portion of each lightbundle) strike the facets of the coupling-out section in each casemultiple times laterally spaced apart, with the result that afterdeflection has taken place (by means of reflection) on the facets thedesired coupling-out is present at the same time as the exit pupil isexpanded.

The coupling-out section thus acts as a reflective coupling-out sectionbecause the reflective facets are provided such that they do notgenerate an intended or a desired diffractive effect.

In the spectacle lens according to the invention the reflectivity of thesplitter layer can increase in the direction from the coupling-in to thecoupling-out section.

Furthermore, the facets can be formed as partially reflective facets. Inparticular, the reflectivity of the facets can increase in the directionfrom the coupling-in to the coupling-out section.

In addition, it is possible for the facets to be formed as reflectivefacets (where possible with 100% reflection).

The facets can be arranged directly next to each other in such a waythat, in top view onto the facets, a (substantially) continuousreflective or partially reflective layer is present. Alternatively, theneighbouring facets can be spaced apart from each other, with the resultthat there are transparent gaps between them (seen in top view).

The reflecting surface can be the front side or a reflecting layerapplied to the front side. Furthermore, it is possible for thereflecting surface to be formed between the two boundary surfaces of thetwo partial bodies.

The reflection on the rear side and/or the reflection on the reflectingsurface can be brought about by total internal reflection.

The facets can be formed on the front side of the spectacle lens body.In particular, the facets can be formed as buried facets. In this case,the depressions which are formed by the facets are filled in with thematerial of the spectacle lens body (or of the corresponding partialbody), with the result that a smooth front side is formed, and inparticular the filling is carried out such that the original curvatureprofile of the front side is also present in the area of the buriedfacets.

The reflecting surface can be formed flat or curved. The splitter layercan also be formed flat or curved.

In the case of a curved formation of the reflecting surface and/orsplitter layer, this can be used to correct imaging errors in theimaging of the light bundles.

The reflecting surface and the splitter layer can be implemented by thesame layer.

The coupling-in section and/or the coupling-out section can have animaging effect.

In addition, it is possible for the coupling-in section to have acollimation effect. The coupling-in section can furthermore berefractive and/or reflective.

It is possible to carry out the coupling into the spectacle lens via anend face which connects the front and rear sides. In particular, the endface can have an imaging function.

The spectacle lens according to the invention can be formed from plasticor glass.

By a facet is meant, in particular, a piece of surface, a surfaceelement or a surface. The piece of surface, the surface element or thesurface can provide the described optical effect of the facet.

The disclosure further includes a display device, including a holderthat can be fitted on the head of a user, an image-generating modulesecured to the holder, which generates an image, and an imaging opticalsystem secured to the holder, wherein the imaging optical systemcomprises a spectacle lens according to the invention and, when theholder is fitted on the head, images the generated image such that theuser can perceive it as a virtual image.

The imaging optical system can comprise the spectacle lens as the onlyoptical element. However, it is also possible for the imaging opticalsystem to comprise, in addition to the spectacle lens, also at least onefurther optical element.

Thus, the further optical element can be e.g. a collimation opticalsystem which is arranged between the spectacle lens and theimage-generating module, with the result that the light bundles from theimage-generating module can be coupled into the spectacle lens ascollimated bundles.

In particular, the imaging optical system can be designed such that theextent of all light bundles in the coupling-in section is as small aspossible. This can be achieved in particular in that the entrance pupilof the imaging optical system is placed in the area of the coupling-insection.

The image-generating module can in particular comprise a two-dimensionalimaging system, such as e.g. an LCD module, an LCoS module, an OLEDmodule or a tilting mirror matrix. The imaging system can beself-luminous or not self-luminous.

The image-generating module can in particular be formed such that itgenerates a monochromatic or a multi-coloured image.

The display device according to the invention can comprise furtherelements known to a person skilled in the art which are necessary forits operation.

It is understood that the features named above and those yet to beexplained below can be used not only in the stated combinations but alsoin other combinations or alone, without departing from the scope of thepresent invention.

It is understood that the features mentioned above and those yet to beexplained below can be used not only in the stated combinations but alsoin other combinations or alone, without departing from the scope of thepresent invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective representation of an embodiment of thedisplay device according to the invention.

FIG. 2 is a detailed sectional view of the first spectacle lens fromFIG. 1.

FIG. 3 is a detailed magnification of a part of the coupling-out sectionaccording to FIG. 2.

FIGS. 4-8 are sectional views of the first spectacle lens to explain thedifferent couplings-out by means of the coupling-out section.

FIGS. 9-11 are views of the exit pupil with the pupil of the eye in thesame position for different field points.

FIGS. 12-14 corresponding views to FIGS. 9-11 with the location of thepupil of the eye shifted horizontally.

FIG. 15 is a representation according to FIG. 3 to explain amodification of the formation of the facets of the coupling-out section.

While the invention is amenable to various modifications and alternativeforms, specifics thereof have been shown by way of example in thedrawings and will be described in detail. It should be understood,however, that the intention is not to limit the invention to theparticular example embodiments described. On the contrary, the inventionis to cover all modifications, equivalents, and alternatives fallingwithin the scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION

In the following descriptions, the present invention will be explainedwith reference to various exemplary embodiments. Nevertheless, theseembodiments are not intended to limit the present invention to anyspecific example, environment, application, or particular implementationdescribed herein. Therefore, descriptions of these example embodimentsare only provided for purpose of illustration rather than to limit thepresent invention.

In the embodiment shown in FIG. 1 the display device 1 according to theinvention comprises a holder 2 that can be fitted on the head of a userand can be formed e.g. in the manner of a conventional spectacles frame,as well as a first and a second spectacle lens 3, 4, which are securedto the holder 2. The holder 2 with the spectacle lenses 3 and 4 can beformed e.g. as sports glasses, sunglasses and/or glasses for correctingdefective vision, wherein a virtual image can be reflected into theuser's field of view via the first spectacle lens 3, as described below.

The spectacle lenses 3 and 4, and in particular the left-hand spectaclelens 3, are only described together with the display device 1 accordingto the invention by way of example. The spectacle lenses 3, 4, or atleast the left-hand spectacle lens, are in each case formed separatelyas a spectacle lens 3, 4 according to the invention. The left-handspectacle lens 3 according to the invention can, naturally, also beformed as the right-hand spectacle lens.

As can best be seen from the detailed sectional view of the first(left-hand) spectacle lens 3 in FIG. 2 (the holder 2 is notrepresented), the display device 1 comprises an image-generating module5, a control unit 6 and a coupling-in optical system 15. Theimage-generating module 5, the control unit 6 and the coupling-inoptical system 15 are represented purely schematically and arepreferably secured to the holder 2. The image-generating module 5 cancomprise e.g. a two-dimensional light modulator (such as e.g. an OLED,CMOS or LCoS chip or a tilting mirror matrix) with a plurality of pixelse.g. arranged in rows and columns. A light bundle 24 can emerge fromeach pixel.

The left-hand spectacle lens 3 comprises a spectacle lens body 7 with acurved front side 8, a curved rear side 9 and an end face 10. Thespectacle lens body 7 is formed in two parts and comprises an innerpartial body 20 and an outer partial body 21. The mutually facing sidesof the two partial bodies 20, 21 have corresponding curvatures, with theresult that they can be connected flat to each other. A reflecting layer22 (e.g. titanium dioxide) which extends from the edge area 12 to thecentral area 13 of the spectacle lens 3 is arranged between the twomutually facing sides. A coupling-in section 25 is formed on the edgearea 12 and a coupling-out section 26 is formed in the central area 13.

As can be seen from the representation in FIG. 2, the light bundles 24run from the image-generating module 5 to the coupling-in optical system15, and enter the spectacle lens (here the inner partial body 20) viathe end face 10 and the rear side 9 such that they are reflected by thereflecting layer 22 to the rear side 9 at an angle at which a totalinternal reflection takes place on the rear side 9. The light bundlesare thus reflected back and forth between the reflecting layer 22 andthe rear side 9 and guided thereby to the coupling-out section 26.

In the area of the coupling-out section 26 the reflecting layer 22 isformed as a splitter layer 22 which reflects a portion of each lightbundle 24 striking it and transmits a portion. The transmitted portionruns through the outer partial body 21 and strikes facets 27 of aFresnel structure 28 which is formed on the front side 9 in the area ofthe coupling-out section 26. The facets 27 are formed partiallyreflective and bring about (by reflection) a beam path folding in thedirection of the splitter layer 22 and the rear side 9 such that thethus-reflected portion of the light bundles 24 passes through thesplitter layer 22 and the rear side 9 (because a total internalreflection on the rear side 9 no longer takes place due to the smallangle of incidence) and is thereby coupled out.

The portion reflected by the splitter layer 22 is totally reflected onthe rear side 9 and thus, as light bundle 24′, again strikes thesplitter layer 22 laterally offset (thus offset in the direction fromthe coupling-in to the coupling-out section 25, 26), where once again aportion is transmitted and a portion is reflected. The transmittedportion of the light bundle 24′ strikes further facets 27 laterallyoffset and is, once again, deflected by these such that a coupling-outtakes place. The portion of the light bundle 24′ reflected by thesplitter layer 22 again strikes the rear side 9 laterally offset and istotally reflected by it. This mode of operation of the splitter layer 22is represented schematically again in the magnified detailed view inFIG. 3, wherein the light bundle 24′ is shown as a dashed line.

In this way, a pupil expander is realized by means of the Fresnelstructure 28, the splitter layer 22 and the rear side 9 in the area ofthe coupling-out section 26, with the result that a large expansion ofthe exit pupil 29 in the lateral direction can be realized.

This enlargement of the exit pupil 29 is carried out in the spectaclelens 3 according to the invention because, due to the very thinformation of the spectacle lens body 7, a bundle diameter of a singlecoupling-out is not sufficient to fill the exit pupil 29. The exit pupil29 can also be called an eyebox. This is the area which is provided bythe display device 1 and in which the user's eye can move and he canstill always perceive the coupled-out image. For each field point (orpixel of the image to be presented), therefore, for example two or threeneighbouring couplings-out are necessary in order to fill the pupil ofthe user's eye positioned in one place in the eyebox 29. These e.g. twoor three couplings-out should therefore be imaged onto the same imagepoint (lying within the resolution of the eye) on the retina. Congruenceis thus to be present. By this is meant in particular that, within theframework of a resolution of the eye of less than 1 min, the samelocation on the retina is struck. It can also be said that the same mainbeam angle is present for these neighbouring couplings-out for one fieldpoint.

The reflecting layer 22 can be formed, in the area between thecoupling-in and the coupling-out section 25, 26 in the same way as inthe area of the coupling-out section 26, as a splitter layer whichreflects a portion of the light bundle striking it and transmits aportion. Only the reflected portion is represented in FIG. 2.Alternatively, the reflecting layer can be formed between thecoupling-in and the coupling-out section 25, 26 such that it acts as atotal internal reflection layer in such a way that from a predeterminedangle of incidence it reflects the light bundles 24 and transmits lightwith an angle of incidence smaller than the predetermined angle ofincidence. In this case a user of the display device can also lookthrough the area of the reflecting layer between the coupling-in and thecoupling-out section 25, 26. Furthermore, the reflecting layer betweenthe coupling-in and the coupling-out section 25, 26 can have any otherdesired reflectivity (greater than 0% to 100%).

The reflecting layer 22 can also extend in the area of the coupling-insection 25. Here, it is preferably formed as a reflecting layer whichcompletely reflects the light bundles incident on it (thus wherepossible a 100% reflection). This is possible without a negative impactfor the user as he does not look through the spectacle lens in this edgearea. In particular, this edge area can e.g. be located in the area ofthe side temple stem or corresponding hinge of the holder 2.

In the described embodiment the coupling-in of the light bundles takesplace partially via the rear side 9 and partially via the end face 10(here the section of the end face 10 of the inner partial body 20).Naturally, the coupling-in can also take place such that it is carriedout either only via the end face 10 or only via the rear side 9.

In FIG. 2, the position 30 of the retina of an eye of a user wearing thedisplay device 1 is also drawn in, to illustrate that the severalcouplings-out for each field point in the retina are congruent.

The Fresnel structure 28 can be formed such that, in addition to thebeam deflection, it also realizes an imaging function. This can beachieved in that a curved reflective surface which has the desiredimaging properties is used as a starting point, and this is thenadjusted by the facets 27. The individual facets 27 can be flat orcurved. Such a procedure is described for example in WO 2010/097442 A1and in WO 2010/097439 A1, wherein the corresponding descriptions andfigures of these published documents are hereby incorporated in thepresent disclosure.

The spectacle lens body 7 according to FIG. 2 can have a thickness offor example 2.0 mm. The magnitude of the radii of curvature of the frontand the rear side 8, 9 is 90 mm. The generated field of view is 10°×4°.PMMA can e.g. be used as material for the spectacle lens body 7. Thediameter, and thus the maximum lateral extent, of the eyebox is 7 mm andat most five couplings-out take place in order to fill the pupil of theeye, wherein the pupil of the eye is assumed to have a diameter of 2 to3 mm.

The splitter layer 22 is in particular formed such that in the area ofthe coupling-out section 26 it has an increasing transmissivity (andthus a diminishable reflectivity) in the direction from the coupling-into the coupling-out section 26.

Furthermore, the shape of the mutually facing sides of the inner andouter partial bodies 20, 21, and thus the shape of the reflecting layer22, for the imaging of the image generated by means of theimage-generating module 5 as a virtual image can be taken into accountin the optimization of the imaging properties which are provided by thespectacle lens 3 according to the invention. Thus, the reflecting layer22 can e.g. be designed as a free-form surface (which has differentcurvatures e.g. in two orthogonal sections or two principal sections),whereby a clear improvement of the imaging quality in the reflection ispossible without affecting the transmitted-light imaging quality (whichis only determined by the front and the rear side 8, 9).

Thus, e.g., the curvature of the rear side 9, which is often used tocorrect defective vision, can be compensated for by correspondingformation of the curvature of the reflecting layer 22, without thetransmitted-light imaging properties being affected. The curvature ofthe front side 8 can e.g. also be taken into account, where necessary,with the result that the virtual image also has the desired defectivevision correction for the user after passing through the rear side 9.

In the representations in FIGS. 4 to 8 the five different couplings-outfor the two edge field points and the field centre are represented. Allfurther couplings-out no longer reach the eye and are therefore also nolonger represented.

In FIG. 9 the illumination of the pupil 31 of the user's eye is shownwhen it is positioned in the centre of the eyebox 29, wherein the fivecouplings-out are labelled A1, A2, A3, A4 and A5. As can be seen fromthe imaging in FIG. 9, the third coupling-out (A3) contributes the mostto the imaging, wherein small portions of the second and fourthcouplings-out (A2, A4) further supplement it.

In FIG. 10, in a similar way to FIG. 9, it is represented whichcouplings-out for the light bundle of the lower field edge (−5°)contribute to the image formation. These are essentially the fourth andfifth couplings-out A4, A5. In FIG. 11 the same representation is shownfor the upper field edge (+5°). This shows that the first and secondcouplings-out A1, A2 are perceived.

In FIGS. 12 to 14 corresponding representations are shown with thelocation of the pupil of the eye 31 shifted horizontally (in they-direction) inside the eyebox 29.

In a modification of the previously described embodiments, thereflecting layer 22 is formed transparent, or not provided, from thecoupling-in section 25 to shortly before the coupling-out section 26,with the result that in this area the light guiding takes place by totalinternal reflection on the front and rear sides 8, 9 (indicated in FIG.2 by the dashed line 40).

Only in the area of the coupling-out section 26 does the reflectinglayer 22 then act as a splitter layer in the already described manner,with the result that a portion of each light bundle 24 striking it istransmitted and a portion is reflected (the beam path is then identicalto the previously described embodiment, with the result that the line 40is no longer drawn in the area of the coupling-out section). Thetransmitted portion strikes the Fresnel structure 28, is deflected by itand thus coupled out towards the exit pupil 29. The reflected portion isreflected on the rear side again towards the splitter layer 22, with theresult that the desired widening of the exit pupil 29 takes place. Thesplitter layer 22 is in turn designed such that it has an increasingtransmittance, and thus a decreasing reflectivity, in the direction fromthe coupling-in to the coupling-out section 25, 26.

In the previously described embodiments the facets 27 are formed on thefront side 8. However, it is also possible for the facets 27 to beformed in the spectacle lens body 7 and in particular in the outerpartial body 21, as indicated in the schematic representation in FIG.15. FIG. 15 substantially corresponds to the representation from FIG. 3,wherein, however, the facets 27 are now formed as buried facets 27 inthe spectacle lens body 7. The depressions formed by the facets 27 arepreferably filled in, with the result that the original curvatureprofile of the front side 8 is present in the coupling-out area 26. Noundesired refractions thereby occur in the area of the coupling-outsection 26 when the surroundings are observed through the spectacle lens3.

In the previous embodiments the facets 27 are formed as partiallyreflective facets. However, they can also be formed as reflective facets(where possible with a reflection of 100%). In this case, atransmitted-light observation is not possible for the observer in thearea of the coupling-out section. However, it is furthermore possible toarrange the partially reflective or reflective facets 27 not only in thedescribed manner, such that, seen in top view, a continuous partiallyreflective or reflective surface is formed, but spaced apart from eachother, with the result that a transmissive area without facets 27 ispresent between two facets 27 in each case. In this case, even if thefacets 27 are formed as reflective facets 27, a transmitted-lightobservation through the coupling-out section 26 is possible as well.

In the described embodiments of the display device 1 according to theinvention the reflection of the virtual image into the user's field ofview takes place via the left-hand spectacle lens 3. Naturally, areflection via the right-hand spectacle lens 4 is also possible. Inaddition, the display device 1 can be formed such that items ofinformation (or virtual images) are reflected in via both spectaclelenses 3, 4. The reflection can take place such that there is athree-dimensional image impression. The spectacle lenses 3, 4 can have arefractive power of zero or a refractive power different from zero (inparticular to correct defective vision). The spectacle lenses 3, 4 canbe produced e.g. from a glass or also from plastic and can, naturally,be used in other display devices that can be fitted on the head of theuser.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiments,it will be apparent to those of ordinary skill in the art that theinvention is not to be limited to the disclosed embodiments. It will bereadily apparent to those of ordinary skill in the art that manymodifications and equivalent arrangements can be made thereof withoutdeparting from the spirit and scope of the present disclosure, suchscope to be accorded the broadest interpretation of the appended claimsso as to encompass all equivalent structures and products. Moreover,features or aspects of various example embodiments may be mixed andmatched (even if such combination is not explicitly described herein)without departing from the scope of the invention.

The invention claimed is:
 1. A spectacle lens for a display device that can be fitted on the head of a user and generate an image, the spectacle lens comprising: a spectacle lens body comprising a front side and a rear side, wherein at least one of the front side and the rear side are curved, and the spectacle lens body further comprising a first partial body and a second partial body, each including mutually facing boundary surfaces which are connected to each other, with, as seen in top view onto the spectacle lens, a coupling-in section in an edge area of the spectacle lens and a reflective coupling-out section, which comprises reflective facets, in a central area of the spectacle lens; and a splitter layer arranged between the two boundary surfaces in the area of the coupling-out section, wherein the spectacle lens is configured to guide light bundles of pixels of the generated image, which are coupled into the spectacle lens via the coupling-in section of the spectacle lens, in the spectacle lens by reflections on the rear side and a reflecting surface lying opposite this to the coupling-out section and coupling them out of the spectacle lens via the coupling-out section, and wherein the splitter layer reflects a portion of light bundles reflected by the rear side towards the rear side and transmits a portion, wherein after reflection on the rear side the reflected portion strikes the splitter layer again and there, once again, is partially reflected towards the rear side and partially transmitted, wherein the transmitted portions strike the facets, which bring about a reflection in the direction of the rear side such that the portions reflected by the facets are coupled out of the spectacle lens through the splitter layer and the rear side, wherein the splitter layer is formed curved.
 2. The spectacle lens according to claim 1, wherein a reflectivity property of the splitter layer decreases in the direction from the coupling-in to the coupling-out section.
 3. The spectacle lens according to claim 1, wherein the facets are formed as partially reflective facets.
 4. The spectacle lens according to claim 3, wherein a reflectivity property of the facets increases in the direction from the coupling-in to the coupling-out section.
 5. The spectacle lens according to claim 1, wherein the reflecting surface is the front side.
 6. The spectacle lens according to claim 1, wherein the reflecting surface is formed between the two boundary surfaces of the first and the second partial bodies.
 7. The spectacle lens according to claim 1, wherein a depression defined by the facets is filled in with material of the partial body, in which the facets are formed, such that a smooth front side is formed.
 8. The spectacle lens according to claim 1, wherein the reflecting surface is formed flat.
 9. The spectacle lens according to claim 1, wherein at least one of the coupling-in section and the coupling-out section have an imaging effect.
 10. The spectacle lens according to claim 1, wherein the coupling-in section has a collimation effect.
 11. The spectacle lens according to claim 1, wherein the coupling-in section is at least one of refractive and reflective.
 12. The spectacle lens according to claim 1, wherein the reflecting surface and the splitter layer are each implemented by a common layer.
 13. A display device, comprising: a holder configured to be fitted on the head of a user; an image-generating module secured to the holder, which generates an image; and an imaging optical system secured to the holder, which comprises a spectacle lens according to claim 1 and which, when the holder is fitted on the head, images the generated image such that the user can perceive it as a virtual image. 